This Small Business Innovation Research (SBIR) Phase I project proposes to create a new, high performance photodetector operating in the near/mid-infrared spectrum. Gallium antimonide (GaSb) will be used to create avalanche photodiodes (APDs) sensitive to wavelengths < 1.7 micron. The GaSb material is a semiconductor with a direct energy bandgap and higher mobility than Silicon. Thus, GaSb has greater photonic absorption and can operate at a higher speed than Silicon. Previously issues regarding high levels of parasitic p-type doping have prevented GaSb from being applied to APD structures. This Phase I program aims to create GaSb layers that no longer have a high native doping level, making APD fabrication possible. The growth techniques demonstrated in this project will be applicable to other similar material systems, allowing practical development of novel devices. Scientific understanding of the electrical characteristics of actualized III-V compound semiconductors will also be improved.
Upon successful completion of the program as a whole, photodetectors operating in the near/mid-IR spectrum (< 2 microns) will be developed that have higher speeds and greater sensitivity than current Silicon APD solutions. High-speed photodetectors will be readily applicable to atmospheric measurement systems, medical diagnostics, astronomical imaging and optical communications. Moreover, modifications to the GaSb material, such as the addition of Indium and Arsenic, can extend the operating spectrum out to longer wavelengths. Based on the knowledge gained in this program, APDs using InGaAsSb could be created which are sensitive photons out to 12 microns.